Bad smell coming from (clean!) toilet

[tigerpug]

I know there is a thread about drains already, so sorry for starting another related one, but ours sounds like a different issue

We have a downstairs toilet which isnt used very much, every so often it starts to smell 'drainy', sorry tmi, its not like someone has just used it, its just a yucky festering smell. Now its started to smell I flush the toilet a few times every day (we always use the upstairs bathroom) but the smell doesn't go. It seems to be made better for a few days when I bleach it, but it keeps coming back. The toilet is clean and isnt blocked i.e. the water drains away.

Im a bit worried that it could be a more serious problem. There is no smell from any other connecting room, or from the upstairs bathroom. The issue we have is the soil pipe from the smelly loo goes under our kitchen to the outside drain.

I think I might need to call a plumber, but before I do that has anyone got any advice? Is there anything like baking soda/drain unblocked that i should try first?

Thanks everyone

We get this smell in our bathroom sometimes, and our builder says it is because gases can come back up the pipes in our system- the smell is actually coming up from the sink rather than the loo. They can fit a valve or something that stops this , we haven't bothered yet as it doen't happen often. It is common in older houses apparently, is yours an older property?

Hi Vix, yes it is old, victorian. We've been here a year and its only recently started to smell. Perhaps nothing to be gained by using drain unblocked then... sigh

You can buy some drain freshener and try that

"the soil pipe from the smelly loo goes under our kitchen to the outside drain."

Do you mean it runs horizontally? So that material might collect, linger and fester in the pipe?

Where is the vent to this pipe?

I get this problem too! And I have a long horizontal run under the kitchen on the soil pipe. Our smell seems to permeate the whole downstairs though. I lifted the floorboards and it's no worse under the boards really. I know there should be a valve on the standpipe that the washing machine drains into and there isn't, so I wondered if it was sewer gases. We also got drain flies last summer. Was rank. Jeyes fluid seemed to sort that out.

An appliance stand-pipe should have a trap, such as a U-bend, but does not need a valve. It needs to be able to equalise pressure.

www.screwfix.com/p/mcalpine-standpipe-appliance-trap-40mm-white/94360?cm_sp=Search--SearchRec--Area2&requestid=318413#=p

Like sink trap, it will prevent sewer gas flowing freely into the room.